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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f9bd764e6a54533c8bc7e70e00e1d1bc83c6a0b51a7cbd650aaac43671d5a126' 
  AND token = 'NtsBfQQDgT4StBoG5GhFQkQU4xLMcfIbQ0IY6lpSq10=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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