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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c9dc3b0012ff274ded03cc521aec8e0de0e68024321f82ee94d23278ba8d2850' 
  AND token = 'Bw51xn8QTNcvhWjIgYIQ/5tiD5dhZ2l9RwXjgBvm6ow=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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