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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50c09adbf8b93ea0a02416869d503fe86eb7e9e2457d347eaa3d84e838ed345c' 
  AND token = 'fOV+BEHX6xw8NtXPZb/w/RI8MgOMBa3DlCcDiyged5c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}