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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bb16d22ad4b58e2d7ba1162f6b18cccb3da649d14f8b422c2ef59b3c582fcb03' 
  AND token = '+buT2ozrEs/KMn8dc1Xh8EvXC2yZlk7YOXkmtrPqy1A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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