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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7dc321ad3aeb2fa03d166c4fee2d2f0661821f8e81e9bf94e11513ce2dd7934d' 
  AND token = 'V7OjMEYVzZrOdQ7UOEthNeIOrg4LMHEQFWTdMBl1SGE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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