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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e3d77ce6c5fe58841aff257da032df98b8f00b28bb9fd192ad4184328d4c1a21' 
  AND token = 'ZZic8xqSc52/1G4LRuDAf8wgT4ljMlQiQSMNDkTuhfI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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