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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cd9c1a2bc3f94a94a512ab8c6f264892c116875334cf3580cae35ffd3ea4b3a0' 
  AND token = 'RdjuBeM67OkwhbAKiTY7z+EvxQ4C8xzyfUkPl9FURIo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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