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SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'c35c7ca8c8ec6b55fc80918796bc489c0f1eab196f2d6feed6d1a71b388d3f75' 
  AND token = '51YiI3ek+pcJ/ta4NjdeWU8szj0uMH5k5D++aWVZTTQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}