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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1902a3d39ba5864ba6f60bb7bce41279c0bd03489b0a8fe25a0abcb8b5990cb5' 
  AND token = 'rSTDjfZjpIjzMlupIM8HMUFinSHvNtb+yy34BpIsRYY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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